Optoelectronic devices, for example photonic integrated circuits (PICs) may be provided in a substrate and manufactured by Silicon Photonics (SiP) technology. Silicon Photonics promises numerous advantages of integrated optical circuits, but continues to suffer from difficulties of coupling light to and from these photonic integrated circuits. Therefore, input-output coupling remains a prerequisite for commercialization of SiP technology.
There are two main technologies that are used for fiber-to-chip coupling. The first technology is based on the use of grating couplers that receive and emit light vertically with respect to the plane of the photonic integrated circuits. The second technology uses edge couplers that terminate waveguides at an edge of the photonic integrated circuits. These fiber-to-chip coupling technologies have their advantages and challenges.
Grating couplers, for example, offer high coupling efficiency, low footprint on a chip, and access to virtually any place on the chip. However, they require fibers to be arranged nearly perpendicularly to the surface of the chip. A method based on the use of grating couplers implies active alignment and results in a non-flat form factor, especially highly undesirable in Data Center applications. Additionally, grating couplers are polarization-sensitive or require complicated and lossy dual-polarization gratings for in-coupled light. Finally, the optical fibers need to be placed with an accuracy of about one micron on the surface of the chip to limit coupling losses.
Edge coupling shares the polarization and accuracy requirements, but here, the fibers are arranged in the plane of the photonic integrated circuits, so that no exorbitant heights of the whole assembly are required, resulting in compact solutions. Another big advantage of side coupling is its extensibility to multi-fiber coupling solutions. However, the mode-fields of Si waveguides, which measure only a few hundreds of nanometers in size, do not match the mode-field of standard single-mode fibers (about 10 μm), so that 3D spot-size converters are required for decent coupling efficiency. To enable coupling with low loss, these converters must be adiabatic, thus requiring a lot of space on a chip comprising the photonic integrated circuit or any additional chip that drives the cost of the photonic integrated circuit and nullifies its compactness.
There is a desire to provide an arrangement for coupling at least one optical fiber to at least one optoelectronic device with low loss. There is also an unresolved need for providing a method to manufacture an arrangement for coupling at least one optical fiber to at least one optoelectronic device with low loss.